Shift control mechanism for change-speed gearing



May 15, 1951 L. A. BlXBY ET AL 2,552,765

SHIFT CONTROL MECHANISM FOR CHANGE-SPEED GEARING Filed May 28, 1949 2 Sheets-Sheet 1 FIG. I

INVENTOR. DONALD S. DENCE LEO A. BIXBY ATTY May 15, 1951 A. BIXBY ETAL SHIFT CONTROL MECHANISM FOR CHANGE-SPEED GEARING 2 Sheets-Sheet 2 Filed May 28, 1949 2M1 (Qt 4AM ATTY Patented May 15, 1951 SHIFT CONTROL MECHANISM FOR CHANGE-SPEED GEARING Leo A. Bixby, Niles, and Donald SJDence, Berrien Springs, Mich., assignors to Clark Equipment Company, Buchanan, Mich., a corporation of Michigan Application May 28, 1949, Serial No. 95,970

1 Claim. (01. 74-473) This invention relates to transmissions, and

low range, and when shifted into high range,

the top three speeds and the high reverse speed are obtained. This is accomplished with the use of only a single gear shift lever and three shift rails. This provides for a minimum requirement of space for the shifting mechanism, and a minimum amount of complex movement of the shift lever. This further simplifies the mounting of the gears in the transmission and the ability to reduce the axial length of the transmission while still obtaining the benefit of a mul tiple speed transmission.

Other objects and advantags of the present invention will appear more fully from the following detailed description which, taken in conjunction with the accompanying drawings, will disclose to those who are skilled. in the art the particular construction and operation of a preferred form of the present invention In the drawings, Figure 1 is a verticalsectional view through a transmission embodying the present invention. 7

Figure 2 is a corresponding transverse sec.- tional view through the transmission, with the gearing and shafts eliminated, but showing the shift forks and shift mechanism.

Figure 3 is a somewhat schematic drawing of the shift yoke mechanism in low range position; and

Figure 4 is a corresponding view of this mechanism in high range position.

Referring now in detail to the drawings, the transmission case is indicated generally at.5 and comprises the end walls 6 and I within which are provided bearing journals of conventional type for supporting the input shaft 8, the intermediate shaft 9, and the output shaft Ill. Each of these shafts, as will be seen, is rotatably sup.- ported in the end walls of the transmission. in spaced parallel relationship.

Shown somewhat diagrammatically and out of position for the sake of clarity, is a reverse idler gear shaft l2 which preferably is located laterally between shafts 9 and Ill.

The input shaft 8 is adapted to carry thecompound gear l3 having a low range gear portion l4 and a high range gear portion 15, therebeing in Figure 2 mounted upon the shift rail l8 and having the lug I9 for engagement by the shift lever indicated generally at 20.

Mounted on the shaft 9 are a plurality of axially spaced gears, including the compound gear 22 having a gear portion 23 adapted to have meshing engagement with the low range gear portion M of gear l3 when this gear is shifted to the left, as shown in Figure 1, and having a small pinion-like gear portion 24. There is an intermediate gear 25 mounted upon the shaft 9 and spaced axially from the gear 22 by means of the sleeve 26. The gear 25 has meshing engagement with the high range gear portion 15 of the gear I 3 when it is shifted to the right from the position shown in Figure 1 which, as shown, is a neutral position. Adjacent the lower end of the shaft 9, there is provided the gear 21 spaced from the gear 25 by means of the spacing sleeve 28 and adjacent to the rear end wall 1 of the transmission.

.The output shaft H), as indicated, has a splined portion within the gear case 5, and has mounted thereon axially sliding gears, the gear 29 being adapted to be shifted axially to the left from the position shown in Figure 1, for meshing engagement with the gear portion 24 of gear 22 to provide a low speed drive to the shaft 10.

When shifted to the right from the position shown in Figure 1, the gear 29 is adapted to mesh.

with the reverse idler gear, shown diagrammatically at 30, which, in turn, has continuous meshing engagement with the gear 25 on shaft 9 to provide a reverse low speed drive to the output shaft. Spaced axially on the shaft l0, there is also provided the compound gear 32, having av first gear portion 33 adapted to mesh with the gear 25 when shifted to theleft to provide a seclond or intermediate speed drive to the shaft [0. The gear portion 34 of the gear 32 is adapted to mesh with gear 21 when gear 32 is shifted to the right to provide third speed drive to the shaft ID. The first, intermediate, and third speed drives thus described, as well as the low speed reverse drive, are all capable of being effected when low range gear portion M of gear I3 is in mesh with gear portion 23 of gear 22, providing low range first, second, third and reverse speeds for the output shaft H) as the gears 29 and 32' are shifted.

However, when the high range gear portion l5 of gear I3 is moved into engagementwith gear 25, a high range drive is then provided to the output shaft 10, the fourth speed in this case being effected by shifting gear 29 to the left. Thus, gear 29, when in engagement with gear 24, can provide either first or fourth speed, depending upon -whetherthe low or high range gear I3 is a suitable annular groove l6 formed in this gear for receiving the ends of the shift fork ll, shown 'mediate lug member 35.

gear portion 34 of gear 32 with gear 21, depend-..

ing upon the position of the low and high range gear I3. Reverse speed in either low or high range is provided by shifting gear 29 to the right;

4 Here, again, it will be noted that both of the lugs 36 and 39 must be returned to neutral position before the low and high range gear I3 can again be shifted out of high range position. Thus, .it is apparent that having once selected the range of speed, this range is maintained while first, second, third and low reverse, or fourth, fifth,

sixth, and high reverse are selectively controlled The shift control mechanism for selecting the- T various speed ranges in the transmission is shown in Figures 2, 3, and 4. The shift lever is preferably provided with a universal mountingwith in the shift tower 35, and has its lower extending end mounted for movement adjacent the shift lug I9 of the shifter fork I'I,,lug 36 of the shift fork 31 mounted upon rail 38, and lug 39 of shift fork 40 mounted upon rail 42. 7

Suitable interlocking balls, indicated diagrammatically at 43 and 44, are provided for interlocking the shift rails to prevent meshing of gears and spring detent balls 45 are provided for detaining the shift rails in their v'arious'shifted positions.

Considering Figure 3 in detail, the lug I9 connected to the shift fork H, is shown here in low range position, with the lower end of the gear shift lever 29 engaged in the slot of the inter- The member I 9 preferably has a spring pressed plunger which must be depressed by the lower end of the shift lever in order to allow engagement of this end in the lug, and when in the position shown in Figure 3, normally maintains the gear shift lever in engagement in the opening 50 of the lug 36 controlling shifter fork 3T." Shifter fork 3'1, in turn, is engaged with gear 32 onshaft Illand fore and aft movement of the shift lever 29 will result in shifting the shift fork 31 axially on the shift rail'38, forward movement of the lug providing for moving gear portion 33 into engagement with gear 25 and rearward movement of the'lug providing for engagement of the gear portion34 in gear 21.

When the shift lever is rocked laterally, the

lower end thereof can be engaged providing lug ,36 is returned to 'a neutral position, with lug 39 having the recess 52 for receiving the lower end of the shift lever. produces Corresponding movement of gear 29 either into first speed position, meshing with.

gear portion 24 of gear 22 or into position engaging reverse idler gear 39. for providing low reverse drive to the output shaft I0. It will be noted that both .of the lugs 36 and 39 must be returned to neutral position before the gearshift lever can be laterally rocked backinto engagement with the lug I9 controlling the low and high of the shift lever into this recess, whereby the intermediate lug 36 can be engaged by the'shift.

lever for fore'and aft movement of gear 32.

Similarly, further lateral rocking movement 7 allows the lower endof the-lever to traverse lug.

3,6 and move intothe recess 55 in lug 59, thereby engaging for movementthe shifter fork All which contr'olsfore and aftmovement of the gear 29.

Fore and aft movement hereby the operator, and that all ars must be returned to neutral position before the shift can be made from either low to high range or vice vers'a. j V

However, it will be noted that this can all be accomplished with only three shift rails and three shifter forks, even though six. forward and two reverse speeds are provided.

It is'therefore believed apparent that vides a very simplified and easily selected gear shift control mechanism for a multiple speed transmission of this type, while still providing the necessary interlocking relationship to prevent any possibility of gear clashing.

'We are aware that other embodiments of this invention may be 'employed'without departing Gear shift means comprising, three parallel shift rails, a shift lug on' one rail having a single recess, shift lugs on each of the other rails hav-' ing a pair ofaxially'spaced recesses, a gear shift lever, means mounting said lever for fore and aft' and lateral rocking movement, said gear shift 35" lever in one lateral position being adapted to engage said recess in said lug on said one 'rail for effecting fore and aft movement of the latter into one of two positions, said lug on said one railbeing I, disposed when in either of said two positions into jacent recess in the lug on either of said other alignment with one of the recesses in said lugs on said other, shift'rail whereby said lever can be laterally rocked out of engagement with said recess in said lug on said one rail into the adtwo shift rails," and a spring biased plunger mounted in said lug on said one rail and project- Number Name a Date 1,513,374 Cozzens Oct. 28, 1924 1,387,943 Padgett Nov. 15, 1932 2,017,101 Lapsley Oct, 15, 1935: 2,214,305 Baker Sep t, 17, 19 40 2,220,197 Ariens Nov. 5, 1940. 2,273,068 Ross Feb. 17,1942 2,301,448 Peterson Nov. 10, 1942, 2,307,857 Rodler Jan. 12,1943 2,316,503 Curtis Apr. .13, 19.43 2,323,384 Eberhard July 6, 1943' FOREIGN PATENTS l Number Country Date 558,392,, Great Britain Jan. 4, 19441 ing into the recess therein at one side thereof for normally biasing said shift leverlaterally outi q of engagement with the latter.

LEO'A. BIXDY. DONALD s. DENCE.

REFERENCES CITED file of this patent: V

. UNITED STATES PATENTS- France June 23, 1936 pro- 

